The invention relates to removal of a barrier layer from an underlying dielectric layer on a semiconductor substrate by performing chemical mechanical polishing (CMP) of the semiconductor substrate.
CMP is performed to remove a barrier layer from an underlying dielectric layer on a semiconductor substrate on which integrated circuits are constructed. Further, CMP is performed to provide the dielectric layer with a smooth, planar polished surface. The substrate to be polished is mounted on a carrier of a polishing machine. The carrier biases the substrate against the polishing pad while the substrate and the polishing pad undergo relative movement. A water based, aqueous polishing composition is applied at an interface of the substrate and the polishing pad.
U.S. Pat. No. 5,676,587 discloses removal of a liner film, referred to herein as a barrier layer, from an underlying dielectric layer, by performing CMP with a neutral pH, silica-based slurry. A slurry is an embodiment of an aqueous polishing composition. During CMP, the barrier layer is removed by abrasion applied by the polishing pad, and by chemical reaction of the barrier layer with the aqueous polishing composition, followed by dissolution in the aqueous polishing composition of the products of chemical reaction. Abrasion is applied by abrasive particles present in an embodiment of the polishing composition. While CMP is performed to remove a barrier layer from an underlying dielectric layer, the underlying dielectric layer undergoes unwanted erosion. Erosion refers to removal of the dielectric layer by the CMP operation. It is desirable to minimize erosion, while CMP is performed to remove a barrier layer from the dielectric layer. Alternatively, it is desirable to remove a controlled amount of the dielectric layer while CMP is performed to remove a barrier layer from the dielectric layer.
U.S. Pat. No. 5,614,444 discloses a slurry having molecules with at least one apolar component. The molecules bond with respective surface silanol bonding groups to form attached, apolar molecules, which apolar molecules are inherently hydrophobic to form a surface film that reduces erosion while CMP is performed.
According to the invention, an aqueous polishing composition has abrasive particles and water of basic pH to remove a barrier layer from a dielectric layer by CMP, and the aqueous polishing composition further comprises; solely polar molecules each having multiple, polar bonding sites forming bonds with bonding groups on a hydrated dielectric layer of a semiconductor substrate, to form an hydrophilic protective film of the polar molecules on the dielectric layer.